Improvement in watch-escapements



J. THOMSON.

WATCH-ESCAPEMENTS.

No- 194,744. Patented Aug. 28,1877.

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I UNITED STATES PATENT OFFICE.

JOHL THOMSON, OF ROCHESTER, NEW YORK.

IMPROVEMENT IN WATCH-ESCAPEMENTS.

Specification forming part of Letters Patent N 0. [94,744, dated August28, 1877 application filed March 29, 1877.

time-pieces.

The balance-wheel of a watch, like the pendulum of a clock, is thedevice which measures or divides the time as indicated by the hands anddial, and upon the accuracy of the actuation of said balance-wheeldepends its perfect performance.

In watches and similar time-keepers as heretofore constructed thebalance-wheel receives its impulses from the escape-wheel through themedium of the escapement-lever directly, and hence is subject to all theirregularities dependent upon imperfections in the main gearing of thewatch, or resulting from changes of temperature, or the decomposition ofthe lubricant and collection of dirt upon the parts. Or, in other words,the balance-wheel, instead of controlling the power, is controlled byit, and thus holds a secondary position, so to speak, instead of thefirst. For this reason a watch, in order to keep correct time, must befinely constructed in every particular, and even when most perfectlyconstructed it cannot be relied upon for more than three or four months,as a general rule.

The object of my invention is to overcome these defects, and produce awatch or other time-keeper that will run with regularity despiteinaccuracies or imperfections of workmanship, change of temperature, orthe decomposition of the oil or collection of dirt; and to this end myinvention consists in imparting the impulses to the balance-wheel by anindependent impulse-spring, set in motion by the escapement-wheel, butacting by its own tension to actuate the balance-wheel, whereby aregular and uniform motion will be transmitted to said balance-wheelentirely independent of the irregularities of the main works of thewatch, as more fully hereinafter described.

In the drawings, Figure 1 is a top or plan view of my invention; Fig. 2,a side elevation;

and Fig. 3 is a detached view of the rollerjournal and lever.

The letter A represents the balance, and 12 its roller-jewel,constructed in the usual manner, and (l the escape-wheel, which isconstructed in the usual manner, with the exception that it is providedwith a series of projections or pins, 0, on one side, corresponding innumber to its teeth, for the purpose to be hereinafter explained. Theletter D represents the lever, the pallets E of which straddle the teethof the escape-wheel, as usual. The working of the pallet-faces e e issubstantially the same as that in common use; but the lever-fork d isquite different, being two or three times wider than the ordinary.Following the motion of the balance, as indicated 7 by the arrow, theroller-jewel b will enter the fork, carrying the lever with it, untilthe escape-wheel tooth is relieved at the pallet c. As the tooth passesover the pallet-face it will force the lever D forward in the samedirection as the movement of the balance. It is this forward movementthat gives to the balance of an ordinary lever-watch its momentum; butin this case the lever-fork is made so wide that no impetus whatever isgiven with this action, the pallet 0 being simply set forwardsufficiently to receive another tooth of the escape-wheel, and the forkplaced in the best position for receiving the rollerjewel on its returnvibration.

The operation j ust described, having relieved the, escapewheel tooth at0, allows the escapewheel to come forward to the pallet e. The manner inwhich the balance-wheel receives its momentum will now be seen. The impulse-spring R, pallet K, andarm F may be in one piece, but are shown asseparate and connected together. As shown, one of the projections orpins 0 on the balance-wheel has depressed the spring by coming incontact with the pallet-face K, holding it in tension until the forwardmovement of the escapewheel deprives it of its support, whereupon itcomes sharply forward, and the stroke end of the arm F, coming incontact with the rollerjewel b, gives to the balance its momentum.

Upon the return vibration of the balance the escape-wheel will be againreleased, and the impulse-spring again depressed into acting position,when the operation first described will be repeated.

In order to have perfect control of the 1110-- tor of the balance, andto do away with ever having to alter the fine hair-spring, I place atthe base of the impu'lse'spring a fine tensionspring, m, passing througha guideway, n, and moved back and forth, as the case may require, by thescrew S.

Upon turning the screw to the right, the grooved head will force thespring through the guideway, adding power to the stroke ortheimpulse-spring. Upon reversing the screw the power is decreased.

It is evident that with the above-described escapement I can produce afine time-keeping watch at a low price. All that is necessary is acommon quality of train-work and mainspring and a finely-adjustedbalance and hairspring.

In the matter of regulation, the balance deriving its sole movement fromthe impulsespring, the first strike is the same as the last, and, beingentirely outside of the fluctuations of the'mainor first power, must rununiformly for a long time.

With this escapement it will be practicable to make watches oflong-runnin g time, and requiring winding but once in a week or longer.It may also be applied to clocks, but, requiring some differentarrangement of details, will form the subject of separate applicationsfor Letters Patent.

I do not intend to limit my invention to the precise detailshereinbefore described, as modifications may be made embodying the sameprinciple.

It will be observed that in this escapement the train-work is stoppedwhen the balance is receiving its impulse, and in action only when thebalance is entirely free of the impulsator and lever.

What I claim, and desire to secure by Letters Patent, is

1. Incombination with the balance-wheel of a watch or other time-keeper,an impulse device operated by the escape-wheel, but acting independentlyof the same and the escape-lever to impart the impulse to thebalance-wheel, whereby a regular and uniform motion is imparted to saidwheel.

2. In combination with the escape-wheel and the balance-wheel of a watchescapement, the adjustable spring R, its pallet K, and extension F,whereby the impulses are imparted to the balance-wheel, substantially asset forth.

3. The combination of the balancewheel A, the lever D, the escape-wheelO, and the impulse device F K R, the whole arranged to operatesubstantially as set forth.

4. In combination with the spring R, the spring m and screw S, foradjusting the tension of the spring R, substantially as and for thepurpose specified.

JOHN THOMSON.

Witnesses:

JOHN MGKEE, JULIUS B. FRASER.

